Move bunker service to Web Worker for persistence (v0.44.6)

- Add bunker-worker.js Web Worker for NIP-46 signing
- Update rollup to build worker as separate bundle
- Move bunker state to stores.js for persistence across tab switches
- Worker maintains WebSocket connection independently of UI lifecycle

Files modified:
- app/web/src/bunker-worker.js: New Web Worker implementation
- app/web/src/stores.js: Added bunker worker state management
- app/web/src/BunkerView.svelte: Use worker instead of inline service
- app/web/rollup.config.js: Build worker bundle separately

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/web/rollup.config.js

@@ -34,7 +34,8 @@ function serve() {
   };
 }
 
-export default {
+// Main app bundle
+const mainConfig = {
   input: "src/main.js",
   output: {
     sourcemap: true,
@@ -95,3 +96,23 @@ export default {
     clearScreen: false,
   },
 };
+
+// Bunker worker bundle (runs in Web Worker context)
+const workerConfig = {
+  input: "src/bunker-worker.js",
+  output: {
+    sourcemap: true,
+    format: "iife",
+    name: "bunkerWorker",
+    file: `${outputDir}/bunker-worker.js`,
+  },
+  plugins: [
+    resolve({
+      browser: true,
+    }),
+    commonjs(),
+    production && terser(),
+  ],
+};
+
+export default [mainConfig, workerConfig];